1 /*
   2  * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 #ifndef SHARE_GC_Z_ZMARKTERMINATE_INLINE_HPP
  25 #define SHARE_GC_Z_ZMARKTERMINATE_INLINE_HPP
  26 
  27 #include "runtime/atomic.hpp"
  28 
  29 inline ZMarkTerminate::ZMarkTerminate() :
  30     _nworkers(0),
  31     _nworking_stage0(0),
  32     _nworking_stage1(0) {}
  33 
  34 inline bool ZMarkTerminate::enter_stage(volatile uint* nworking_stage) {
  35   return Atomic::sub(nworking_stage, 1u) == 0;
  36 }
  37 
  38 inline void ZMarkTerminate::exit_stage(volatile uint* nworking_stage) {
  39   Atomic::add(nworking_stage, 1u);
  40 }
  41 
  42 inline bool ZMarkTerminate::try_exit_stage(volatile uint* nworking_stage) {
  43   uint nworking = Atomic::load(nworking_stage);
  44 
  45   for (;;) {
  46     if (nworking == 0) {
  47       return false;
  48     }
  49 
  50     const uint new_nworking = nworking + 1;
  51     const uint prev_nworking = Atomic::cmpxchg(nworking_stage, nworking, new_nworking);
  52     if (prev_nworking == nworking) {
  53       // Success
  54       return true;
  55     }
  56 
  57     // Retry
  58     nworking = prev_nworking;
  59   }
  60 }
  61 
  62 inline void ZMarkTerminate::reset(uint nworkers) {
  63   _nworkers = _nworking_stage0 = _nworking_stage1 = nworkers;
  64 }
  65 
  66 inline bool ZMarkTerminate::enter_stage0() {
  67   return enter_stage(&_nworking_stage0);
  68 }
  69 
  70 inline void ZMarkTerminate::exit_stage0() {
  71   exit_stage(&_nworking_stage0);
  72 }
  73 
  74 inline bool ZMarkTerminate::try_exit_stage0() {
  75   return try_exit_stage(&_nworking_stage0);
  76 }
  77 
  78 inline bool ZMarkTerminate::enter_stage1() {
  79   return enter_stage(&_nworking_stage1);
  80 }
  81 
  82 inline bool ZMarkTerminate::try_exit_stage1() {
  83   return try_exit_stage(&_nworking_stage1);
  84 }
  85 
  86 #endif // SHARE_GC_Z_ZMARKTERMINATE_INLINE_HPP